The endotracheal tube, used to ensure adequate oxygenation (i.e., ventilation) of a conscious or unconscious patient, is a mainstay of internal medicine. Various improvements of the basic endotracheal tube have been described in the literature, including the addition of an inflatable cuff that encircles the distal end of the tube to assist in holding the tube in place within the trachea of the patient. (See, for example, U.S. Pat. No. 3,794,043 granted to McGinnis, which also describes means for inflating the cuff externally and a separate inflatable member that allows the medical practitioner to gauge the pressure of the internal cuff to avoid pressure necrosis of the involved tissues of the trachea.) Other improvements of the endotracheal tube have been described. (See, for example, U.S. Pat. No. 3,848,605 granted to Harautuneian and Penny; U.S. Pat. No. 4,134,407 granted to Elam; and, more recently, U.S. Pat. No. 4,751,924 granted to Hammerschmidt and Zumbruch).
The intubation or insertion of an endotracheal tube into a patient to supplement, assist, or dislace a patient's normal breathing is a common medical procedure that is performed in many settings, including an accident scene, in a rescue vehicle or ambulance, in an emergency room, or a regular operating room. Thus, it is not that unusual for the site in which the procedure is being attempted to be bustling with medical and rescue personnel, along with the noise caused by their vehicles or equipment, not to mention the general pandemonium caused by the people, themselves, shouting and yelling instructions to one another.
It is under such circumstances that the medical practitioner frequently has to perform the intubation procedure. Typically, the endotracheal tube is inserted intraorally, if the patient is unconscious. (If the patient is conscious or has an intact gag reflex, then the tube is inserted intranasally to provide more comfort for the patient). To verify proper insertion, the medical practitioner will typically do one of two things: first, he or she may place the proximal end of the tube to his or her ear to listen for the sounds made by the patient's breathing; or, second, he or she may place the end of the tube close to the bottom portion of his or her forearm or wrist in an attempt to feel the movement of air.
All the while, there is the possibility that the patient may cough, sneeze, excrete or, otherwise, expel aerosols, saliva, mucus, and other bodily excretions, especially through the tube and, hence, into the medical practitioner's ear or against his or her exposed skin. What is more, the patient may be suffering from a communicable disorder borne by some microbial, fungal, or viral disease-causing agent. Thus, there is clearly a need for a means by which the medical practitioner can perform and verify a successful intubation without reliance on his or her auditory or hearing acuity or skin sensitivity.
Yet, while the intubation procedure may be extremely difficult in an emergency setting, this common procedure can be quite tricky even in the relative "quiet" of an operating room in the absence of sophisticated fiber viewing optics (e.g., a laryngoscope) that allow the medical practitioner to determine by internal visualization the proper passage into which the endotracheal tube is to be inserted. Such a "blind" insertion (i.e., without the optics) has in the past been aided by use of one of two devices. The first is a whistling device that produces a sound that is created by the rapid passage of air through the device. Unfortunately, such a device is of no help if the patient is in acute respiratory distress (in which case the patient is hardly breathing, if at all), cardiac arrest, or if the patient's breathing is otherwise very shallow or intermittent.
A second device consists of a color change monitor that attaches to the proximal end of the endotracheal tube after intubation. If the distal end of the endotracheal tube is positioned in the trachea, carbon dioxide gas which is exhaled by the patient causes the color monitor to exhibit a color reading that is consistent with proper levels of carbon dioxide gas production. If, instead, the endotracheal tube is located in the esophagus, the color reading will reflect inadequate levels of carbon dioxide, and the medical practitioner will then attempt to re-intubate the patient. While providing a visual signal, the color change monitor requires a minimum of six full breaths for an accurate color change to develop (up to 20-25 seconds after the endotracheal tube as hopefully been positioned properly and the air cuff, if equipped, inflated). Besides requiring a relatively extended period for providing a color reading, which approaches the ACLS allowable anoxic intubation time of 30 seconds, the above-mentioned color change monitor requires careful comparison of the various colors that are produced by the device against standard color charts. Morevover, the color change monitor is relatively expensive, adding about $40 to the cost of the procedure.
Hence, there remains a need for providing a simple, quick, and effective means of facilitating the insertion of an endotracheal tube and of verifying proper placement in the trachea of the patient.